(1) Field of the Invention
The present invention is directed to friction reducing polymer coatings.
(2) Description of the Prior Art
In recreational activities that involve moving an object that has a surface in contact with liquid water, ice or snow, friction between the surface of the object and the water, snow or ice creates an undesirable loss of speed and decrease in maneuverability. Moreover, additional force or power needs to be added to overcome the effects of these frictional losses. Lubricants are used to decrease the friction between the object surface and the water, snow or ice. In activities such as skiing or snowboarding, a coating of a wax or similar material is applied to the surface of the ski or snow board that is in contact with the snow or ice to reduce friction.
Various compositions of waxes have been used including lacquer-waxes and paraffin waxes. The waxes in general adhere well to the surface of the ski or snowboard, are moisture repellent, have a low adhesion to snow and are easily applied. U.S. Pat. No. 4,343,863 is directed to a drag-reducing ski wax that is particularly useful on ultra-high performance skis and is applied directly as an exterior coating to the ski running surface base layer that will come into direct friction contact with snow. A poly(alpha-olefin) is incorporated into a wax formulation to reduce ski drag.
All waxes, however, easily wear off ski surfaces and need to be frequently reapplied. Therefore, repeated applications of the wax to the contact surface are required. In addition, waxes sometimes require heating during application. In many instances, the wax must be applied to a completely dry surface. Thus, “in-the-field” application or re-application of wax coatings is difficult or impossible, in particular where the surface is moist.
In addition to applying waxes to the contact surface of a ski or snow board, the contact, surfaces, which are generally bonded to the ski body, can be modified to provide for a level of lubrication. For example, the contact surface can contain a lubricating filler, for example powdered graphite or molybdenum disulfide. U.S. Pat. No. 5,409,622 is directed to a surface lubricant that contains over 50 vol. % boron nitride (hexagonal), with the remainder of the composition being bonding agents comprised of single or mixed oxides or organics, the boron nitride composition being from about 36 wt. % to about 99 wt. %. This lubricant is suitable for topical applications in a thin layer to various sports objects. The lubricant can be applied in the form of a stick, paste or powder or be incorporated into waxes. While such particulate lubricants help to reduce drag between the ski running surface and the snow, the spaced apart particles do not provide a continuous lubricating surface. They also tend to easily wear off the ski surface due to friction with the snow.
Another type of lubricant that can be used to decrease friction and increase performance is a drag reducing polymer. Drag reducing polymers have been applied in many different types of applications where friction or frictional loss needs to be minimized. Drag reducing polymers have been applied to the interior of pipes and have resulted drag reductions of up to 80% using long chain polymers at concentrations in the 5 parts per million range. The Alaskan oil pipe line, for example, uses long chain polymers to reduce frictional drag. This reduction in frictional drag increases the amount of flow through the pipe, reducing the number of pumping stations required to transfer the oil through the pipe line. Polymer coatings are also used on razors to provide a lubricant between the skin and the blade. Lubricating polymer materials have also been used for crowd control. By spraying the lubricating polymer on a street or parking lot, walking or running across the surface would be impossible due to the lubricious surface created by the polymer, and anyone attempting to cross the surface on foot would fall down and have to crawl.
U.S. Pat. No. 4,093,268 is directed to a plastic drag reducing surfacing material containing a lubricating polymer. A ski surfacing plastic base layer is provided that acts as a rigid, plastic, non-water soluble matrix for the lubricating additives. A long carbon chain, thermoplastic, water soluble polymer is disposed and interdispersed with the plastic, non-water soluble matrix. The polymer slowly dissolves and leaches out of the surrounding plastic matrix upon contact with the microlayer of water from the snow or ice on which the ski moves, to form a liquid, polymer containing film. The film acts as a continuous, frictionless boundary lubricant to reduce drag and increase speed. This surface attempts to rely on the leaching of the lubricant from the plastic matrix in order to achieve the desired lubrication. The amount and rate of leaching, however, may provide an insufficient amount of lubrication.
Therefore, the need exists for a lubricant that can be easily and repeatedly applied in the field to a frictional contact surface. A sufficient amount and concentration of the lubricant is applied so that the lubricant is easily and readily available to provide a sufficient amount of lubrication.